Abstract
GntR-type transcriptional regulators are involved in the regulation of various biological processes in bacteria, but little is known about their functions in Sinorhizobium meliloti. Here, we identified two GntR-type transcriptional regulator genes, gtrA and gtrB, from S. meliloti strain 1021. Both the gtrA1 mutant and the gtrB1 mutant had lower growth rates and maximal cell yields on rich and minimal media, as well as lower cell motility on swimming plates, than did the wild-type strain. Both mutants were also symbiotically deficient. Alfalfa plants inoculated with wild-type strain 1021 formed pink elongated nodules on primary roots. In contrast, the plants inoculated with the gtrA1 and gtrB1 mutants formed relatively smaller, round, light pink nodules mainly on lateral roots. During the first 3~4 weeks post-inoculation, the plants inoculated with the gtrA1 and gtrB1 mutants were apparently stunted, with lower levels of nitrogenase activity, but there was a remarkable increase in the number of nodules compared to those inoculated with the wild-type strain. Moreover, the gtrA1 and gtrB1 mutants not only showed delayed nodulation, but also showed markedly reduced nodulation competition. These results demonstrated that both GtrA and GtrB affect cell growth and effective symbiosis of S. meliloti. Our work provides new insight into the functions of GntR-like transcriptional regulators.
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- Investigation of Nitrogen Fixation Efficiency in Diverse Alfalfa Varieties Utilizing Sinorhizobium meliloti LL2
Yilin Han, Wenjuan Kang, Shangli Shi, Jian Guan, Yuanyuan Du, Fuqiang He, Baofu Lu, Ming Wang
Agronomy.2024; 14(11): 2732. CrossRef - The GntR-like transcriptional regulator HutC involved in motility, biofilm-forming ability, and virulence in Vibrio parahaemolyticus
Yangyang Li, Weidong Sun, Quan Wang, Ying Yu, Ying Wan, Kai Zhou, Rong Guo, Xiangan Han, Zhaoguo Chen, Weihuan Fang, Wei Jiang
Microbial Pathogenesis.2022; 167: 105546. CrossRef - Two homologous Salmonella serogroup C1-specific genes are required for flagellar motility and cell invasion
Xiujuan Zhou, Bin Liu, Yanhong Liu, Chunlei Shi, Pina M. Fratamico, Lida Zhang, Dapeng Wang, Jianhua Zhang, Yan Cui, Ping Xu, Xianming Shi
BMC Genomics.2021;[Epub] CrossRef - Characterization of MocR, a GntR-like transcriptional regulator, in Bradyrhizobium japonicum: its impact on motility, biofilm formation, and soybean nodulation
May Nyan Taw, Hae-In Lee, Sang-Ho Lee, Woo-Suk Chang
Journal of Microbiology.2015; 53(8): 518. CrossRef - Directed Construction and Analysis of a Sinorhizobium meliloti pSymA Deletion Mutant Library
Svetlana N. Yurgel, Michael W. Mortimer, Jennifer T. Rice, Jodi L. Humann, Michael L. Kahn
Applied and Environmental Microbiology.2013; 79(6): 2081. CrossRef - PCR identification of Salmonella serogroups based on specific targets obtained by comparative genomics
Bin Liu, Lida Zhang, Xinna Zhu, Chunlei Shi, Jing Chen, Weibing Liu, Xiaohua He, Xianming Shi
International Journal of Food Microbiology.2011; 144(3): 511. CrossRef - Identification of a TRAP transporter for malonate transport and its expression regulated by GtrA from Sinorhizobium meliloti
Ai-Min Chen, Yong-Bao Wang, Sun Jie, Ai-Yuan Yu, Li Luo, Guan-Qiao Yu, Jia-Bi Zhu, Yan-Zhang Wang
Research in Microbiology.2010; 161(7): 556. CrossRef -
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Sinorhizobium meliloti
-Alfalfa Symbiosis
Nataliya Gurich, Juan E. González
Journal of Bacteriology.2009; 191(13): 4372. CrossRef